There are some environments in which it is desirable that a user located within that environment is alert. Example environments include a control room centre, a pilot's cockpit, an operating theatre, a conference room and a car.
However, these environments are not always conducive for causing a user to remain alert. The lighting in certain environments, such as the ones mentioned above, may be reduced due to the natural setting of the sun or through artificial means, such as a dimmer switch. This reduced lighting makes it more difficult for a user to remain focused on a task whilst in that environment. As reduced lighting adds to the problem of a user feeling less alert/more tired, a simple solution has been to use light to make the user more alert.
It has long been known that light has an effect on the human body. For example, an increase in sunlight on a human can lead to an increase in vitamin D, which allows calcium to be better absorbed. It is also known that light can have an effect on how alert a person feels (this is linked to the circadian responses in a person).
Known methods for improving the alertness of a person using light falls into two categories. The first category focusses on setting the intensity of the light (e.g. using a very bright light for a continued period of a couple of hours to readjust circadian parameters). The second category focusses on setting the wavelength of the light (e.g. using a blue enhanced light to inhibit the production of melatonin).